Enable -Wundeclared-selector on ios.

ios/chrome/app/safe_mode/safe_mode_egtest.mm

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <EarlGrey/EarlGrey.h>
 #import <XCTest/XCTest.h>
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 #include "base/mac/scoped_nsobject.h"
@@ skipping 37 matching lines @@
   NSString* tryAgainPrimaryAction =
       [tryAgain uppercaseStringWithLocale:[NSLocale currentLocale]];
   id<GREYMatcher> tryAgainMatcher =
       [GREYMatchers matcherForButtonTitle:tryAgainPrimaryAction];
   [[EarlGrey selectElementWithMatcher:tryAgainMatcher]
       assertWithMatcher:grey_notNil()];
 }
 
 }  // namespace
 
+// Expose internal class methods for swizzling.
+@interface SafeModeViewController (Testing)
++ (BOOL)detectedThirdPartyMods;
++ (BOOL)hasReportToUpload;
+- (NSArray*)startupCrashModules;
+@end
+
 // Tests the display of Safe Mode Controller under different error states of
 // jailbroken-ness and whether a crash dump was saved.
 @interface SafeModeTestCase : ChromeTestCase
 @end
 
 @implementation SafeModeTestCase
 
 // Tests that Safe Mode crash upload screen is displayed when there are crash
 // reports to upload.
 - (void)testSafeModeSendingCrashReport {
@@ skipping 83 matching lines @@
   NSString* message =
       [NSLocalizedString(@"IDS_IOS_SAFE_MODE_NAMED_TWEAKS_FOUND", @"")
           stringByAppendingString:@"\n\n    iAmBad\n    MJackson"];
   AssertMessageOnPage(message);
   AssertTryAgainButtonOnPage();
   AssertMessageNotOnPage(
       NSLocalizedString(@"IDS_IOS_SAFE_MODE_SENDING_CRASH_REPORT", @""));
 }
 
 @end